China and India both put out less co2 than the US and much much less on a per capita basis and more on a per dollar of GDP.
The point you are missing is that Greenland was called that because at the time of its discovery, it was Green and thought possible for a human colony.
To the title of the article, if anyone solves the co2 problem, it will be the US via technology.
However, one thing I never see anyone talk about is working on the enviornment in the hot spots. I shudder when I see sandstorms in Iraq at 130 degrees. Instead of expensive meetings in Greenland, some gritty conservation work to improve the enviornment and cool things down in certain areas is indicated imho.